1. Field of the Invention
This invention relates to an improved electrical double layer energy storage device. More particularly, this invention relates to the use of particular carbons in the electrodes of a double layer energy storage devices to improve electrical discharge time.
2. Description of the Art
This invention relates to the electrical energy storage devices of the general type disclosed in U.S. Pat. Nos. 3,536,963, 3,634,736 and 3,648,126, hereby incorporated by reference. These devices are comprised of a pair of electrodes, at least one of which is a carbon paste electrode, a separator, and an ion insulating connector. The carbon paste electrode is generally manufactured by mixing finely divided carbon particles with an electrolyte to form a paste and then subsequently forming an electrode from the paste.
While activated carbons having high surface areas are employed in conventional carbon paste electrodes, it has not been previously recognized that certain types of activated carbons have a direct effect upon the electrical discharge time of double layer energy storage devices. It has now been discovered that by employing carbons which exhibit specific pore volumes and median pore radiuses, the electrical discharge time of the cells can be significantly extended.